Abstract TheaimofourproposalistoelucidatethemechanismsthatlinktranscriptionofspecificRNAsinthe nucleustotheirtranslation(RNAprocessing).?Wehaveidentifiedandcharacterizedanovelandhighly conservedgene,?Zfrp8/PDCD2,?andshownthatitisessentialinstemcellsinflies,mouse,andhuman,and thatitisalsorequiredforgrowthofcancercells.Wediscovered?Zfrp8/PDCD2?isrequiredforthenuclearexport ofselectmRNAsandTEtranscripts.Alsoitinteractswiththesmallribosomalsubunitandformsacomplex withmRNAbindingproteins.OurdatasuggestthatZfrp8/PDCD2controlssubcellularlocalizationofselect RNAsandtheassociationofmRNARNPswithribosomes.WealsohaveidentifiedTet/TET1asanew Zfrp8/PDCD2interactingprotein.Invertebrates,TETproteinsfunctioninDNAdemethylationconverting 5methylcytosine(5mC)into5hydroxymethylcytosine(5hmC),modificationsthatarenotdetectedin DrosophilaDNA.ArecentstudyshowsthatvertebrateTetproteinscanalsoconvert5mrCto5hmrCinRNA. Inspiredbythisdiscovery,wehaveshownthat5hmrCalsoexistsinfliesanddependsonTetactivity.We hypothesizethatTetmodifiesspecifictranscriptsandregulatestherecruitmentofZfrp8totheseRNAs,so controllingtheirprocessingandtranslation. Weproposetotestthishypothesisbyacombinationofmolecular/biochemicalandgenetic experiments.Wewillidentify5hmrCmodifiedtranscriptstranscriptomewideandstudytheirintegrity,levels, andlocalizationinwildtypeandmutanttissues.WewillmaptheTetbindingsitesonDNAandcomparetheir locationto5hmrCmodifiedtranscripts.Finally,wewilltesthow?Tet?and?Zfrp8?affectribosomaloccupancyof mRNAsandestablishhow?Tet?and5hmrCaffecttheirtranslation.Inadditiontoinvestigatingthemechanismby which?Tet?and5hmrCregulateRNAmetabolismandhowZ?frp8?affectstheprocess,wewilldeterminethe importanceofbothgenesindevelopmentandstemcelldifferentiationbystudyingthemutantphenotypesof new?Tet?allelesand?Tet?and?Zfrp8KD?tissues.BecauseoftheconservationofbothTetandZfrp8/PDCD2our resultsarelikelytoshedlightonthesameprocessinmouseandhuman.